The present invention relates generally to agricultural round balers which form cylindrical bales using one or more movable belts and/or rollers disposed in a bale-forming chamber and, more particularly to an improved system for tensioning the movable belts.
Round balers have become quite prevalent for their capability of producing a conveniently sized cylindrical bale, very often automatically wrapped with a sheeting material such as net or film. Crop material, such as hay, is picked up from the ground as the baler travels across the field, and is fed into an expandable chamber where it is rolled up to form a compact cylindrical hay package.
Prior art round balers generally have an expandable bale chamber defined by a pair of fixed sidewalls, and a plurality of side-by-side belts cooperating with a series of transverse rolls, mounted between a pair of pivotally mounted arms commonly known as a sledge. The chamber includes an inlet opening in the front through which crop material is fed. Also included is a pair of take up arms pivotally mounted on the main frame, between which arms multiple of guide rolls are journalled. A biasing force is applied on the take up arms to urge the outer surfaces of the guide rolls against the belts to maintain belt tension and prevent slack from occurring in the belts during expansion and contraction of the chamber.
It is known to provide a round baler density system to apply increased tension on the belts in order to create a densely packed bale. A hydraulic density cylinder with a controlled fluid release limits the rate of bale chamber expansion and provides a degree of crop compaction during baling. The amount of compaction may be varied by adjusting the fluid release rate, often in the form of a pressure relief valve which restricts the extension of the density cylinder by forcing fluid through a variable relief. When the bale reaches a desired size and is discharged, mechanical springs acting on the take up arms are typically employed to return the hydraulic cylinder to its initial position and provide a biasing force on the take up arms so a new bale forming cycle may commence.
Problems arise as the tailgate is opened in preparation to discharge the completed bale. The geometry of the belt take-up system requires some slack in order to open the tailgate and discharge the bale. If the density system is resisting slackening movement of the belts during tailgate opening, the tailgate opening apparatus must overcome not only the force necessary to lift the tailgate, but the resistive force applied to further extension of the belt take-up mechanism. This results in increased power input required during the tailgate opening sequence, and skewing of the tailgate and belts.
It would be desirable to provide a system that would release the resistive force applied on the belts by the bale density system when the tailgate is released for opening. Additional advantages would be realized by a system that would automatically release the resistive force based on positioning of the tailgate latching system and restore the bale density to a normal operation configuration once the tailgate is fully opened or begins to close. Still further advantages would be realized by a density system release mechanism that could be easily incorporated into existing baler density systems with minimal alteration of the existing bale density tensioning system.